areaportals on lsd

well im working on areaportals for my grate doors (the ones you see at the spawns for blu on dustbowl and goldrush) and well you can look through just fine but as soon as you walk to where the area portal would be it looks like you forgotten a skybox (which im not mind you) when everything is skipping a repeating the image of what you are seeing, and when you go though it everything is fine. Now I looked at the way valve did it and mine isnt much different from the way they did it and i cant find a reason for this problem. Any input would be helpful

You have a leak, not to the void, but a leak between world brushes somewhere which is not sealing your areaportal. Load your pointfile and you will see the exact place. It's probably not the areaportal brush itself that is leaking, but somewhere there is a small opening somewhere that is allowing it to leak back to itself. The sides need to be sealed against world brushes but the two opposite faces cannot share the same map space. They need to be entirely closed off with world brushes.